linux-kernel - Re: [PATCH 01/10] fs crypto: add basic definitions for per-file encryption

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Date:	Thu, 10 Mar 2016 21:00:25 -0800
From:	Dan Williams <dan.j.williams@...il.com>
To:	Jaegeuk Kim <jaegeuk@...nel.org>
Cc:	Randy Dunlap <rdunlap@...radead.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-f2fs-devel@...ts.sourceforge.net,
	"Theodore Ts'o" <tytso@....edu>
Subject: Re: [PATCH 01/10] fs crypto: add basic definitions for per-file encryption

On Mon, Feb 29, 2016 at 5:35 PM, Jaegeuk Kim <jaegeuk@...nel.org> wrote:
> On Sun, Feb 28, 2016 at 09:41:22PM -0800, Randy Dunlap wrote:
>> On 02/25/16 11:25, Jaegeuk Kim wrote:
>> > This patch adds definitions for per-file encryption used by ext4 and f2fs.
>> >
>> > Signed-off-by: Jaegeuk Kim <jaegeuk@...nel.org>
>> > ---
>> >  include/linux/fs.h       |   8 ++
>> >  include/linux/fscrypto.h | 239 +++++++++++++++++++++++++++++++++++++++++++++++
>> >  include/uapi/linux/fs.h  |  18 ++++
>> >  3 files changed, 265 insertions(+)
>> >  create mode 100644 include/linux/fscrypto.h
>> >
>> > diff --git a/include/linux/fs.h b/include/linux/fs.h
>> > index ae68100..d8f57cf 100644
>> > --- a/include/linux/fs.h
>> > +++ b/include/linux/fs.h
>> > @@ -53,6 +53,8 @@ struct swap_info_struct;
>> >  struct seq_file;
>> >  struct workqueue_struct;
>> >  struct iov_iter;
>> > +struct fscrypt_info;
>> > +struct fscrypt_operations;
>> >
>> >  extern void __init inode_init(void);
>> >  extern void __init inode_init_early(void);
>> > @@ -678,6 +680,10 @@ struct inode {
>> >     struct hlist_head       i_fsnotify_marks;
>> >  #endif
>> >
>> > +#ifdef CONFIG_FS_ENCRYPTION
>> > +   struct fscrypt_info     *i_crypt_info;
>> > +#endif
>> > +
>> >     void                    *i_private; /* fs or device private pointer */
>> >  };
>> >
>> > @@ -1323,6 +1329,8 @@ struct super_block {
>> >  #endif
>> >     const struct xattr_handler **s_xattr;
>> >
>> > +   const struct fscrypt_operations *s_cop;
>> > +
>> >     struct hlist_bl_head    s_anon;         /* anonymous dentries for (nfs) exporting */
>> >     struct list_head        s_mounts;       /* list of mounts; _not_ for fs use */
>> >     struct block_device     *s_bdev;
>> > diff --git a/include/linux/fscrypto.h b/include/linux/fscrypto.h
>> > new file mode 100644
>> > index 0000000..b0aed92
>> > --- /dev/null
>> > +++ b/include/linux/fscrypto.h
>> > @@ -0,0 +1,239 @@
>> > +/*
>> > + * General per-file encryption definition
>> > + *
>> > + * Copyright (C) 2015, Google, Inc.
>> > + *
>> > + * Written by Michael Halcrow, 2015.
>> > + * Modified by Jaegeuk Kim, 2015.
>> > + */
>> > +
>> > +#ifndef _LINUX_FSCRYPTO_H
>> > +#define _LINUX_FSCRYPTO_H
>> > +
>> > +#include <linux/key.h>
>> > +#include <linux/fs.h>
>> > +#include <linux/mm.h>
>> > +#include <linux/bio.h>
>> > +#include <linux/dcache.h>
>> > +#include <uapi/linux/fs.h>
>> > +
>> > +#define FS_KEY_DERIVATION_NONCE_SIZE               16
>> > +#define FS_ENCRYPTION_CONTEXT_FORMAT_V1            1
>> > +
>> > +#define FS_POLICY_FLAGS_PAD_4              0x00
>> > +#define FS_POLICY_FLAGS_PAD_8              0x01
>> > +#define FS_POLICY_FLAGS_PAD_16             0x02
>> > +#define FS_POLICY_FLAGS_PAD_32             0x03
>> > +#define FS_POLICY_FLAGS_PAD_MASK   0x03
>> > +#define FS_POLICY_FLAGS_VALID              0x03
>> > +
>> > +/* Encryption algorithms */
>> > +#define FS_ENCRYPTION_MODE_INVALID         0
>> > +#define FS_ENCRYPTION_MODE_AES_256_XTS             1
>> > +#define FS_ENCRYPTION_MODE_AES_256_GCM             2
>> > +#define FS_ENCRYPTION_MODE_AES_256_CBC             3
>> > +#define FS_ENCRYPTION_MODE_AES_256_CTS             4
>> > +
>> > +/**
>> > + * Encryption context for inode
>> > + *
>> > + * Protector format:
>> > + *  1 byte: Protector format (1 = this version)
>> > + *  1 byte: File contents encryption mode
>> > + *  1 byte: File names encryption mode
>> > + *  1 byte: Flags
>> > + *  8 bytes: Master Key descriptor
>> > + *  16 bytes: Encryption Key derivation nonce
>> > + */
>> > +struct fscrypt_context {
>> > +   char format;
>> > +   char contents_encryption_mode;
>> > +   char filenames_encryption_mode;
>> > +   char flags;
>> > +   char master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
>> > +   char nonce[FS_KEY_DERIVATION_NONCE_SIZE];
>>
>> how about u8 instead of char?
>
> It seems that it needs to user u8 instead of char for other variables as well.
> I'll take a look at all the usages.

I think it needs to be __u8 otherwise I get this in a userspace program:

In file included from test/blk_namespaces.c:17:0:
/usr/include/linux/fs.h:256:2: error: unknown type name ‘u8’
  u8 version;
  ^
/usr/include/linux/fs.h:257:2: error: unknown type name ‘u8’
  u8 contents_encryption_mode;
  ^
/usr/include/linux/fs.h:258:2: error: unknown type name ‘u8’
  u8 filenames_encryption_mode;
  ^
/usr/include/linux/fs.h:259:2: error: unknown type name ‘u8’
  u8 flags;
  ^
/usr/include/linux/fs.h:260:2: error: unknown type name ‘u8’
  u8 master_key_descriptor[FS_KEY_DESCRIPTOR_SIZE];
  ^